The present invention relates to a whisker-reinforced ceramic material with improved performance particularly when machining heat resistant materials.
It is well-known in the art that the fracture toughness of a ceramic material can be increased by addition of monocrystalline hair crystals (whiskers) and/or platelets. A material consisting of SiC-whiskers in an alumina matrix is disclosed in U.S. Pat. No. 4,543,345. U.S. Pat. No. 4,867,761 discloses the use of whiskers of carbides, nitrides or borides of Ti and/or Zr in an alumina matrix. Through U.S. Pat. No. 4,849,381, a cutting tool insert comprising a mixture of whiskers and platelets is known.
U.S. Ser No. 08/089,560 and 08/090,960 (our references: 024000-963 and 024000-965), herein incorporated by reference, discloses a method of manufacturing a whisker-reinforced ceramic body comprising 2-50% by volume whiskers and/or platelets in a ceramic matrix by powder metallurgical methods, i.e., dispersion in a suitable liquid, granulation, compaction and sintering. If the granulation is performed by freeze granulation, a ceramic body with homogenous structure with essentially no granule borders is obtained.
JP-A-4-149062 discloses a composite ceramic containing TiN-particles and SiC-whiskers in an alumina matrix.
U.S. Pat. No. 4,746,635 discloses sintered ceramic composite-containing alumina, zirconia and SiC-whiskers.